Objective: The objective of the study is to study the usefulness of electrocardiography in localizing the culprit vessel in acute ST-elevation myocardial infarction (STEMI) and to assess the diagnostic accuracy of the electrocardiogram (ECG) findings by comparing them with coronary angiographic findings. Materials and Methods: This study is prospective observational study, conducted on fifty patients in tertiary care center attached to medical college. Patients with ST-segment elevation in ECG was evaluated to identify culprit vessel and later correlated with their coronary angiography. Results: Among fifty patients in the study, 34 had anterior wall, and 16 had inferior wall myocardial infarction. ST↑ >1 mm in V4R, ST↓V3/ST↑LIII <0.5 were equally sensitive for diagnosing proximal right coronary artery occlusion. For left circumflex occlusion, ST elevation in lead III >lead II was the most sensitive and ratio of ST↓V3/ST↑LIII >1.2 was the most specific criterion. In anterior wall STEMI, 52.9% patients had occlusion proximal to first septal (S1), 17.6% had occlusion proximal to first diagonal (D1), 8.8% had occlusion distal to S1, and 20.5% had occlusion distal to D1. Q wave in aVL had maximum sensitivity for identifying occlusion proximal to D1 and Q wave in leads V4-V6 for occlusion distal to S1. Conclusion: The admission ECG in patients with STEMI is valuable not only for determining early reperfusion treatment, but also provides important information to guide clinical decision-making.